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Biomedical subjects

R W Brower

Publications and source records attributed to R W Brower.

At least 37 records · Page 2Linked to original sources
PubMed1985

Comparison of preoperative, operative and postoperative variables in asymptomatic or minimally symptomatic patients to severely symptomatic patients three years after coronary artery bypass grafting: analysis of 423 patients.

During a follow-up period of 3 years, among a consecutive series of 423 patients who gave informed consent for recatheterization both 1 and 3 years after coronary artery bypass grafting, the incidence of severely symptomatic patients with New York Heart Association class III or IV was 19% (79 of 423). The predictive value of approximately 80 clinical, angiographic and perioperative variables was too low to be of clinical value. Adverse clinical outcome was associated with a high closure rate of the grafts. Forty-six percent of the patients could not undergo reoperation because of unsuitable coronary anatomy. With intensive medical therapy half of these patients improved to functional class I or II, while of those patients who were reoperable 32% improved to class I or II with intensive pharmacologic treatment instead of reoperation. The nonresponders underwent reoperation, which resulted in improvement of symptoms to functional class I or II in most (83%).

Adult↗
PubMed1985

Aorto-coronary bypass surgery in 62 patients with severe left ventricular dysfunction--a follow-up study.

Long-term follow-up of 62 consecutive patients with severe left ventricular dysfunction (ejection fraction = less than 0.30) and disabling angina pectoris following aorto-coronary bypass surgery was investigated. Prior to surgery all patients had angina pectoris and a history of remote myocardial infarction, 35% were in congestive heart failure (CHF). Significant stenoses in 3 major coronary vessels were present in 51 patients (82%). An average of 3.5 grafts per patient were employed. Operative mortality (30 days) rate was 4.8% (3 patients) and 13 patients died during the following period. The average follow-up was 37 months (range: 6 to 116 months). At follow-up, the 5-year survival probability for these patients was 70% (SD = 9%). Thirty-one patients (67%) of the 46 survivors had complete relief of angina, but signs of CHF were still evident in 17 patients (36%). Compared to patients with ejection fractions above 0.30% (surgical mortality 1.4% and 5-year survival rate 94% (SD = 3%] the outcome of coronary artery bypass grafting in patients with poor left ventricular function showed a significantly higher surgical mortality (P = 0.03) and impaired long-term survival (P = 0.02). However, aorto-coronary bypass grafting can be performed in patients with severe left ventricular dysfunction with reasonable relief of angina and with an acceptable surgical mortality.

Adult↗
PubMed1985

Effect of long-term oral nifedipine therapy on left ventricular regional wall function at rest and during supine bicycle exercise.

15 patients, 1 to 3 year after coronary bypass surgery, underwent symptom limited supine bicycle exercise tests without nifedipine and after acute and chronic (3 months) administration of the drug. Haemodynamic variables were monitored as was epicardial marker motion, using biplane cineradiography during exercise, the markers having been implanted at the time of surgery. We found significant (P less than 0.001) reductions in end-diastolic and end-systolic regional dimensions at maximal exercise after oral nifedipine, associated with a significant reduction in exertional angina, which persisted during long-term treatment. No adverse effects of the drug were observed.

Administration, Oral↗
PubMed1985

Prognosis of patients with different peak serum creatine kinase levels after first myocardial infarction.

The extent to which patients with low peak serum creatine kinase (CK) at their first myocardial infarction differ from patients with high CK levels in terms of risk for subsequent ischaemic events was investigated in 266 patients who survived the first 48 h from the onset of infarction. All patients were followed up for one year. Four groups were formed based on peak CK less than or equal to 200, 201-400, 401-800 and greater than 800 IU l-1. During follow-up the incidence of mortality was 15% (N = 39), non-fatal re-infarction 9% (N = 23), and angina 53% (N = 140). Hospital mortality was significantly higher (P less than 0.02) in the highest CK-group (16%), but the incidence of non-fatal re-infarction, angina pectoris and late mortality was similar in the four groups. In hospital survivors, ischaemic ST-changes during pre-discharge symptom limited bicycle stress test and multiple vessel disease were equally distributed in all four groups. We conclude that while hospital mortality is directly related to peak CK, there is no relationship between peak CK and late mortality, non-fatal re-infarctions, or recurrent angina. Accordingly, diagnostic and therapeutic procedures in the individual patients are not influenced by the amount of serum CK released during acute infarction.

Creatine Kinase↗
PubMed1985

Left ventricular function during transluminal angioplasty: a haemodynamic and angiographic study.

The response of left ventricular function, was studied in a series of patients undergoing percutaneous transluminal coronary angioplasty (PTCA). From 4 to 6 balloon inflations procedures per patient were performed with an average duration per occlusion of 51 +/- 12 sec (mean +/- SD), total occlusion time 252 +/- 140 sec. Analysis of left ventricular (LV) haemodynamics showed that the relaxation parameters peak negative rate of change in pressure and the early time constant of relaxation responded earliest to acute coronary occlusion while other parameters such as peak pressure, LV end-diastolic pressure, and peak positive rate of change of pressure responded more gradually and suggested a progressive depression in myocardial mechanics during the entire procedure. LV angiogram available in 14 patients indicate an early onset of asynchronous relaxation concurrent with the early response in peak -dP/dt and the time constant of early relaxation. All haemodynamic parameters fully recovered within minutes after the end of PTCA. The results of this study indicate no permanent dysfunction to global or regional myocardial mechanics, after PTCA with 4 to 6 coronary occlusions each lasting 40 to 60 seconds.

Angiography↗
PubMed1985

Limitations of a QRS scoring system to assess left ventricular function and prognosis at hospital discharge after myocardial infarction.

The value of a QRS scoring system derived from 12 lead electrocardiograms to estimate left ventricular ejection fraction was assessed in a prospective study of 285 hospital survivors of myocardial infarction. In these patients both the QRS score and ejection fraction were measured by radionuclide ventriculography at discharge. The correlation between ejection fraction and QRS score was weak. In 22 patients who died during six to 12 months follow up the ability of the ejection fraction and QRS score to predict mortality was assessed in terms of sensitivity, specificity, predictive value of a positive and negative test, and efficiency. For ejection fraction less than 40% and a QRS score greater than or equal to 6 sensitivity was respectively 73% and 64%, specificity 73% and 56%, predictive value of a positive test 18% and 11%, predictive value of a negative test 97% and 95%, and efficiency 73% and 56%. Both ejection fraction and QRS score may be used to identify patients at low and high risk during one year follow up, but, contrary to initial expectations, the QRS score appears to be of little value in estimating ejection fraction and is less accurate than ejection fraction in predicting late survival in hospital survivors of myocardial infarction.

Adult↗
PubMed1985

Surgical versus non-surgical management of patients soon after acute myocardial infarction.

Of 510 patients admitted to hospital with acute myocardial infarction, 34 had coronary artery bypass grafting before discharge (6-43 days (median 20) after infarction). The patients who were given grafts generally had a smaller infarction with less functional impairment than the 476 patients who were not. The outcome of coronary artery bypass grafting was investigated in a retrospective matched pair study. Patients were matched on the basis of the presence of postinfarction angina, left ventricular ejection fraction, location of the infarction, peak creatine kinase activity, Killip clinical class, and severity of coronary disease with 34 patients who were given medical treatment only. At one year follow up fewer of the operated patients had symptoms than did the matched non-operated patients. Survival at one year in the operated and non-operated groups respectively was 94% vs 91%; angina within one year occurred in 3% vs 68%; congestive heart failure in 3% vs 6%; and 0% vs 32% were referred for later bypass grafting or coronary angioplasty. It is concluded that coronary artery bypass grafting can be performed safely soon after myocardial infarction provided that left ventricular function is not seriously compromised. Such treatment is more effective than medical treatment for relief of angina during the first year after infarction.

Angina Pectoris↗
PubMed1984

Problems and pitfalls in a clinical research data management system.

The problems and pitfalls encountered in the computerized data bank for the Netherlands Coronary Surgery (NCS) study are reviewed. This study involved 848 patients seen before coronary artery surgery and at 1 and 3 yr after surgery. Nineteen data forms were used resulting in maximally 1142 variables per patient. The importance of quality control is emphasized as well as the efficient transfer of information from data bank to statistical processing.

Coronary Artery Bypass↗
PubMed1984

Predischarge stress test after myocardial infarction in the old age: results and prognostic value.

The aim of this study was to evaluate the results of predischarge stress testing in the elderly, and to assess the prognostic value of the test during one-year follow-up. The database consisted of 48 patients older than 64 years of age and 109 patients 55-64 years of age, who survived acute myocardial infarction, out of 532 consecutive patients admitted for myocardial infarction. Stress-test results were not different in the two groups. During one-year follow-up mortality was 6% in the younger patients and 4% in the older group, and the incidence of non-fatal reinfarctions was 8% in both groups. Mortality was best predicted by the extent of blood pressure rise (43 +/- 26 mmHg in survivors vs 19 +/- 15 mmHg in non-survivors, P less than 0.001). Stress-test results were no more predictive when non-fatal reinfarction was added to mortality as an end-point. We conclude that for patients in whom the stress test is not contraindicated, age does not affect stress test results, the extent of blood pressure rise during a stress test is the best single predictor of mortality, stress tests are not predictive of reinfarctions.

Aged↗
PubMed1984

Ineligibility for predischarge exercise testing after myocardial infarction in the elderly: implications for prognosis.

This study describes the clinical profile and prognosis of elderly patients not eligible for predischarge exercise testing. The database consisted of 133 patients 55-64 years of age, and 111 patients older than 64 years of age who survived an acute myocardial infarction. Follow-up was one year. In the younger age group, 24 (18%) patients were unable to perform the test, in contrast to 63 (57%) of the elderly subjects. In these two groups, one-year mortality rates were 13% and 37%, compared with 6% and 4% for the respective patients eligible for stress testing. Clinical profile and radionuclide ejection fraction between ineligible patients in both age groups were similar. Ejection fraction measurement was the best predictor of late mortality in those patients who did not have an exercise test. It is concluded that ineligibility for predischarge exercise test identifies a high-risk group, especially in patients older than 64 years of age.

Aged↗
PubMed1984

Prediction of mortality in hospital survivors of myocardial infarction. Comparison of predischarge exercise testing and radionuclide ventriculography at rest.

The relative merits of resting ejection fraction measured by radionuclide angiography and predischarge exercise stress testing were compared for predicting prognosis in hospital survivors of myocardial infarction. Two hundred and fourteen survivors of myocardial infarction out of 338 consecutive patients with acute myocardial infarction were studied over a 14 month period. Hospital mortality was 13% (45 of 338) whereas 19 additional patients out of 214 died in the subsequent year (9%). High, intermediate, and low risk groups could be identified by left ventricular ejection fraction measurement. Mortality was 33% for nine patients with an ejection fraction less than 20%, 19% for 58 patients with an ejection fraction between 20% and 39%, and 3% for 147 patients with an ejection fraction greater than 40%. Mortality was high (23%) in 47 patients who were unable to perform the stress test because of heart failure (19) or other limitations (28). The patients could be stratified further into intermediate and low risk groups according to the increase in systolic blood pressure during exercise: six deaths occurred in 46 patients with a blood pressure increase of less than 30 mm Hg and two deaths occurred in 121 patients with an increase greater than or equal to 30 mm Hg. Maximum workload, angina, ST changes, and ventricular arrhythmias were less predictive than blood pressure changes. It is concluded that the prognostic value of radionuclide angiography at rest and of symptom limited exercise testing is similar. The latter investigation should be the method of choice since it provides more specific information for patient management.

Aged↗
PubMed1984

Left ventricular performance, regional blood flow, wall motion, and lactate metabolism during transluminal angioplasty.

The response of left ventricular function, coronary blood flow, and myocardial lactate metabolism during percutaneous transluminal coronary angioplasty (PTCA) was studied in a series of patients undergoing the procedure. From four to six balloon inflation procedures per patient were performed with an average duration per occlusion of 51 +/- 12 sec (mean +/- SD) and a total occlusion time of 252 +/- 140 sec. Analysis of left ventricular hemodynamics in 19 patients showed that the relaxation parameters, peak negative rate of change in pressure, and early time constants of relaxation, responded earliest to short-term coronary occlusion (peak effect at 17 +/- 7 sec) while other parameters, such as peak pressure, left ventricular end-diastolic pressure, and peak positive rate of change in pressure, responded more gradually, suggesting a progressive depression of myocardial mechanics throughout the procedure. Left ventricular angiograms, available for 14 patients, indicated an early onset of asynchronous relaxation concurrent with the early response in peak negative dP/dt and the time constant of early relaxation. All hemodynamic functions fully recovered within minutes after the end of PTCA. Mean blood flow in the great cardiac vein and proximal coronary sinus and the hyperemic response were measured in 20 patients. Before PTCA mean flow in the great cardiac vein was 69 +/- 17 ml/min and in the coronary sinus it was 129 +/- 34 ml/min. Reactive hyperemia (great cardiac vein) was 55% after the first PTCA and 91% after the third. A more pronounced reaction was observed when the residual functional coronary stenosis was reduced in subsequent dilatations. Arteriovenous lactate difference appeared constant during the first two occlusions (control +0.11 mmol/liter, first PTCA -0.87 mmol/liter, and second PTCA -0.82 mmol/liter) and did not increase during subsequent occlusions. Within minutes after the procedure lactate balance was again positive, demonstrating the reversibility of the metabolic disturbances after repeated ischemia. The results of this study indicate that there is no permanent dysfunction of global or regional myocardial mechanics, myocardial blood flow, or lactate metabolism after PTCA with four to six coronary occlusions of 40 to 60 sec.

Angioplasty, Balloon↗
PubMed1983

A model of asynchronous left ventricular relaxation predicting the bi-exponential pressure decay.

A new model for the pressure relaxation of the left ventricle is proposed. The model presumes that the myocardium relaxes asynchronously, but that when regions begin to relax, after a delay, the local wall stress decays as a mono-exponential process. This formulation results in an apparently bi-exponential process (two time constants) which has been previously reported. It is shown that the ratio of the two time constants (T2/T1) can be interpreted as the fraction of the myocardium which relaxes synchronously. Data are presented illustrating the Model during transient coronary occlusion in patients undergoing percutaneous transluminal coronary angioplasty.

Angioplasty, Balloon↗
PubMed1983

Angina pectoris, one to 10 years after aortocoronary bypass surgery.

The incidence of angina pectoris (AP) after bypass surgery was assessed in 1041 patients operated on consecutively between 1971 and 1980. Of the 977 survivors, 920 (94%) participated in the study with a followup time varying from 1 to 10 years (mean 3.5 years). Post-operative angina pectoris was present at 1 year in 277 patients (30%), at 3 years in 46%, at 8 years in 50%. The pain limited usual physical activities in 17.5%, 30% and 25%, respectively at these times. Nonetheless, 89% of the respondents felt improved by surgery. Factors without predictive value for late outcome were sex, number of pre-operative diseased vessels, and pre-operative ejection fraction. A correlation was found between post-operative AP and younger age at surgery in the males only (P less than 0.001); between AP and patency rate of the bypass graft (P less than 0.005) and with the status of the coronary arterial tree at three years post-operatively (P less than 0.001) in both sexes. The percentage of patients with recurrent AP increased with time after surgery up to 3 years, but remained stable thereafter. In conclusion, post-operative AP seems initially related to decreased functioning of the bypass graft, later to progression of coronary sclerosis in the native circulation.

Adult↗
PubMed1983

Influence of intracoronary nifedipine on left ventricular function, coronary vasomotility, and myocardial oxygen consumption.

The effect of intracoronary nifedipine on regional and global left ventricular performance, coronary vasomotility, and myocardial oxygen consumption is reported. Left ventricular pressures and volume indices of contractility and relaxation were simultaneously recorded in five patients without coronary artery disease. In these patients, nifedipine in the left main coronary artery not only delayed (+115 ms) anterior wall contraction but also slowed (3.5 vs 1.9 cm/s) and depressed it (-26%), resulting in a depression of global left ventricular ejection. This asynchrony and depression of regional contraction is considered to be responsible for the slowed isovolumic contraction and relaxation of the whole ventricle. In 10 other patients with coronary artery disease, coronary sinus blood flow and myocardial oxygen consumption were measured before and after intracoronary nifedipine. The observed decrease in myocardial oxygen consumption (-28%) depended primarily on a decrease in contractility and left ventricular performance. In a third study group of 12 patients with coronary artery disease, the effects of intracoronary nifedipine on the coronary vasomotility of 40 coronary segments (normal, prestenotic, stenotic, poststenotic) were quantitatively determined. Left ventricular haemodynamics and coronary sinus saturation were monitored while the cineangiograms were recorded before and after nifedipine. Nifedipine provoked vasodilatation of the normal (+10.3%), prestenotic, stenotic (+4 to 30%), and poststenotic (+16.4%) coronary segments, which persisted after the disappearance of its direct effects on the myocardium. This transient regional "cardioplegic" effect of nifedipine, associated with an increase in coronary blood flow, a reduction in myocardial oxygen consumption, and a vasodilatation of the epicardial vessels is likely to be beneficial during temporary coronary occlusion such as occurs in spasm or transluminal angioplasty.

Adult↗
PubMed1982

Afterload reduction with nifedipine in aortic insufficiency.

The acute hemodynamic effects of nifedipine were assessed in 12 patients with severe aortic insufficiency during control conditions and 30 minutes after administration of nifedipine (20 mg sublingually). Left ventricular end-diastolic pressure decreased from 19 +/- 8 (mean +/- standard deviation) to 9 +/- 5 mm Hg (probability [p] less than 0.0001), mean aortic pressure from 98 +/- 12 to 80 +/- 9 mm Hg (p less than 0.00001), systemic vascular resistance from 1,135 +/- 280 to 794 +/- 176 dynes . s. cm-5 (p less than 0.0002) and rate-pressure product from 11,732 +/- 1,727 to 10,022 +/- 1,103 mm Hg beats/min (p less than 0.01). Forward cardiac index increased by 24 percent, from 3.8 +/- 1.1 to 4.4 to 0.8 liters/min per m2 (p less than 0.04). Left ventricular end-diastolic volume, ejection fraction and total stroke work index did not change significantly. Regurgitant fraction, measured in five patients, changed parallel with systemic vascular resistance. Left ventricular function was maintained while both preload and afterload were decreased. Regurgitant flow was moderated and myocardial oxygen demand decreased. This hemodynamically favorable condition, due to nifedipine, is clinically important and suggests the need for further therapeutic trials.

Adult↗